Structural Effects of Sodium Hypochlorite Solution on RACE Rotary Nickel-Titanium Instruments: An Atomic Force Microscopy Study

Abstract

Objective: The aim of this study was to investigate the effect of sodium hypochlorite immersion on the surface characteristics of RaCe rotary nickel-titanium instruments using atomic force microscopy (AFM). Study design: Four new RaCe instruments were used in this study (two 30.06 and two 30.02). One 30.06 and one 30.02 instrument were immersed in sodium hypochlorite solution for 5 min. Surface topography of the instruments was evaluated using the AFM. The instruments were analyzed on 11 points along a 3-mm section. Root mean square (RMS) values were used to compare the topographic deviations. The data were analyzed using Student t test. Results: Mean RMS values for NaOCl measurements were higher than the measurements on new files, and the difference was statistically significant (P < .01). Conclusion: The AFM results show that NaOCl causes deterioration on the surface of RaCe instruments and should be used with care during clinical use because of the risk of unexpected failure. © 2008 Mosby, Inc. All rights reserved.